If you ran ads with 500,000 displays and only 13 or so clicks, you did something horribly wrong. Facebook ads have a value because they can be ultra targeted. There are many ways ways you could have made a mistake, for instance, demographics that were too unspecific, bad images, not enough variations (i use 10+ sometimes), bad copy, etc.
I like to look at the comparison of google ads vs facebook ads as such: If you want to provide a service/product to people who are seeking that solution, use Google ads. And if you want to go to the targeted demographic directly and present your solution/product/message, use Facebook.
An example would be if you sold wedding services in miami. You could go on facebook and target women 25-35 who are engaged and live in miami. The ads would display only for the targeted demographic and would likely have a good click-through rate. Or you could go into google adwords and buy terms related to wedding services miami or zipcode+wedding service. The differences here are that a woman in the younger demographic is much more likely to be spending hours on facebook and only minutes on a google search.
In addition, google also has incredibly high competition for some of the more lucrative keywords and it is getting increasingly more competitive in local search, now requiring a top 7 ranking to really matter in the local listings.
Also, never underestimate the cpm (cost per thousand) displays of facebook ads to the targeted demographic. They work great for events like concerts and other events when simple awareness is key. A good image also helps a lot, as I run ads with the same text and different images and see dramatic differences in the number of clicks.
It's difficult for me to believe that "nobody cares about Facebook ads and no one clicks on them" because Facebook Ads (and Google Adwords/Adsense) operate as markets, with a bidding system on price. I almost don't want to post this because the more people who know about and use facebook ads, the higher the price rises. Their prices have been steadily rising over the last year as more and more business try them out. They do work, but not for every product and not for every demographic. But people wonder how facebook can have such a high valuation, because they underestimate the amount of direct access and data Facebook has to over 500 million people.
The ads do work, but to create a good campaign requires knowledge of the platform, and experience in marketing, advertising, and copywriting. Laypeople assume they don't need marketers and can do buys themselves, and more cheaply, but usually end up spending more. The true gold in online advertising though, comes from what happens after the person clicks.